|Posted by Amine Slimani on November 4, 2011 at 7:15 AM|
When I started writing about USB to SPDIF converters around two years ago, I faced a lot of skepticism over at head-fi. Some of the usual complaints were rather similar to the following: How is it possible that two bit perfect transports can sound any different from one another? How is it possible that gigabytes of data can be transported over USB cables in hard drives without the loss of a single packet while USB cables are reported to sound different from one another by audiophiles?
Wouldn’t placebo be the most probable explanation for these reported differences? Isn’t the simplest answer the most probable one according to Occam’s razor principle?
While some people tend to view the world in term of simplicity, unconsciously basing their reasoningon false or incomplete assumptions, the world can turn out to be different and far more complex than they imagined.
When one does a little research, one will easily find that the razor principle does not actually tell exactly that the simplest answer is probably the most probable one, but it tells something rather more subtle. That is, the razor is a principle that suggests we should tend towards simpler theories until we can trade some simplicity for increased explanatory power. Hence, contrary to the popular summary, the simplest available theory is sometimes a less accurate explanation.
Similarly, while the most simple and probable explanation to the fact that audiophiles hear differences between digital transports and USB cables might appear at first sight to be the result of a placebo effect or simply pure hallucination, a deeper study of the problem can tell us that USB hard drives are dealing with data in blocks while USB converters are dealing with data in real time. This subtle but important distinction explains the difference between two apparent similar phenomena. Henceforth, while jitter is not an issue when are dealing with datain blocks in the case of USB hard drives, it can become critical andproblematic when we are dealing with (real time) audio data.
Of course, there are today fewer people arguing against the existence of jitter in USB audio. But those same “objectivists” people are telling us now that even though jitter exists and can be measured, there is no way it can be “heard” by people in away that it becomes audible in listening sessions.
So to sum up what we have covered, Audiophiles were hearing differences between bit perfect digital sources that should not have existed in the first place according to the general consensus of that time. Once we established that there is a theory behind USB sources and cables measuring different, we are now being told by the same “smart” and “objective” people that the levels of jitter we are dealing with are too small to be audible anyway. In order to make their point they would often cite a couple of AES studies made a long time ago about levels of audibility of jitter. Granted those papers were conducted in a “scientific” matter but the assumptions they make about what is “adequate” for an experiment and the equipment they used in their experiment render those studies pretty useless for any audiophile.
So, by now people should have a good idea of where I stand on the subject. Let us move on onto how to select a USB converter in this crowded market.
Personally, I have experimented with close to a dozen USB converters, mostly entry and mid-level converters. While (simple) measurements seem to sometimes contradict at firstsight what we hear in amplifiers, preamplifiers and even DACs, it seems that jitter (in its various forms) is a relatively good indicator of what to expect from a USB converter when you cannot listen to it before making the purchase. Usually, the better sounding converters are also the one that had the lowest jitter numbers (when those numbers are available), with a few exceptions to the rule.
After using mainly a battery powered Hiface (Jkeny’s MK1) and a heavily tweaked Audio-gd Digital Interface in my system for while, I felt that there was perhaps still the possibility to improve upon certain aspects of the sound.
Given that I wasn’t able to listen to the Audiophilleo 2 before making my purchase, I relied on people’s impressions and jitter numbers published on Audiophilleo’swebsite. Reading about the Audiophilleo, I could see that the designers thought about many things (everything?) regarding the matter of how to squeeze the most performance from the USB port of an audio computer. The asynchronous method of transmission of usb data, the high quality dual fixed dual clocks (one for 44.1K multiples and a second one for 48K multiples), the ultra-fast transformer-less output stage as well as the ultra-low published jitter numbers were all good signs of what to expect fromthe Audiophilleo 1 and 2.
Audiophilleo’s website is very well made and full of explanations about their product in particular and digital transmission in general, so I won’t go in any sort of full description about the product as it has already been (well) covered elsewhere.
Before moving on to the review, I thought it could be interesting to copy the early impressions I posted the day after I received the unit. People not interested in the early impressions can probably skip this part and go directly to the review.
“I picked up the Audiophilleo2 yesterday and I have been very impressed about what I heard so far.
First, I should probably mention that the Audiophilleo2 was very well packed and that it looked amazing. The pictures on the website do not do justice to the wonderful finish of the aluminium casing.
Now, let's move to the sonics. I have been using mainly a heavily tweaked Audio-gd DI these past few weeks, which I thought was on par or slightly better than the JKeny MK1. Some of the tweaking involved getting an upgraded clock (from Tentlabs), an aftermarket power cord (from the French Hifi Cables & Cie maker) for the external power supply and some vibration dampening (from Herbie's audio lab). Also, I would plug the external power supply into my Bada power filter, and I would use the Musiland 01 USD (with a high end Hifi Cables Sobek digital cable) to drive the Digital Interface from its spdif input instead of using the usb input.
As one might notice, I tried to squeeze as much performance from the DI as it was possible for without resorting to soldering and various DIY modifications.
However, despite all the tweaking described above, Ifelt that my system still lacked some of the harmonic richness and natural warmth one can hear in live events (or extremely good systems).
I was positively surprised when I first plugged the Audiophilleo2 into my system and I heard some of that natural warmth I had been chasing through various tweaks.
I had read various reports about the Audiophilleo2 before acquiring it and some people described it to be slightly on the sharpside of neutral, so I was a bit cautious about that possible aspect of thepresentation. I was actually very relieved when I heard no obvious tonalbalance shift when moving from the DI to the Audiophilleo2.
However, what I heard was an increase in the richness of the sound. Unlike comparing the Sennheiser HD650 to the Beyer T1, in which the former is richer but hazier than the latter, the move from the DI to the Audiophilleo2 brought improvements in both natural (recorded) warmth and accuracy of timber.
The other two areas of improvement that "jumped to my ears" so far are the increase in soundstage & imaging accuracy, and low level details.
Overall, the gains in both refinement and accuracy are amazing.
I am very impressed with what Audiophilleo has achieved.The guys over at Audiophilleo seem to have accomplished what we do not seem to witness very often in the audiophile world: they made a product that measures extremely well, that sounds awfully good, and that is very convenient to use.”
Equipment used for the Review:
Computer source: HP Pavillon DV6 (Core i7,8GB), Windows 7 64bits SP1, Foobar2000 v1.1.8, Wasapi output
Transports: Audiophilleo 2, Kingrex UD384, Jkeny’s modified Hiface MK1, Audio-gd Digital Interface (w/ Tentlabs upgrade clock), Teralink X2, Musiland Monitor 01 USD, EMU 0404 USB
DACs: Audio-gd DAC-19 DSP (with DSP1 V5), Audio-gd Fun, Kingrex UD384
Amplifiers: Audio-gd C2, Little Dot MKIII
Headphones: ALO recabled Beyerdynamic T1, Sennheiser HD650 with Artisan Silver Dream upgrade cable
Digital interconnects: Hifi Cables Sobek BNC, OyaideDB-510 BNC, Wireworld Ultraviolet USB
Analog Interconnects: Artisan Ultimate Silver Dream RCA, Norse Audio custom 8 conductor UP-OCC ACSS, Deep Sounds SPS ACSS, Kimber PBJ RCA
Power filtration: Bada LB-5600 Filter, Essential Audio Tools Noise Eater, Essential Audio Tools Pulse Protector, Supra Mains distributor
Power cords: Hifi Cables & Cie PowertransPlus (x2), Hifi Cable & Cie SimpleTrans, Olflex power cords
Vibration Control: Aktyna ARIS decoupling feet, Maple and Acrylic Platforms, E&T rack, Stabren Damping pads, Sandbox, Brass cones, Vibrapod, Yamamoto Ebony footers and Various Herbie’s Audio Labs tweaks
Reference Tracks used for this review:
Mahler - Symphony n 5- Decca - 16/44
Sol Gabetta - Schostakowitsch Cellokonzert Nr. 2/Cello - 16/44
Vivaldi - Concertofor 2 violins - Carmignola/Mullova - 16/44
Natalie Dessay - Italian Opera Arias - Emi Classics -16/44
Puccini - La Boheme - Decca - 16/44
Glenn Gould - The Goldberg Variations 1981 - 16/44
The Essential James Bond - City of Prague Philharmonic orchestra - 16/44
The Dave Brubeck Quartet - Take Five - HDCD - 16/44
Diana Krall - Live in Paris - 16/44
Norah Jones - Come Away With Me - 16/44
Patricia Barber -Companion - 16/44
Johnny Cash - TheEssential - 16/44
Soundrama - "ThePulse" Test CD - 16/44
High Resolution quality:
Rachmaninoff Dances -HD Tracks - 24/96
Mozart Violin Concertos - Marianne Thorsen - 2L - 24/96
Dunedin Consort -Messiah - Linn Records - 24/88
Keith Jarrett - Paris/ London - Testament - 24/96
Jazz at the Pawnshop- HD Tracks - 24/88
Alison Krauss and Union Station - Paper Airplane - 24/96
Ella Fitzgerald /Louis Armstrong - Ella & Louis - 24/96
Diana Krall - Fromthis Moment on - 24/88
Diana Krall - TheGirl in the Other Room - 24/96
The World's GreatestAudiophile Vocal Recordings - Chesky - 24/96
The Kinks - One forthe Road Live - 24/96
The Eagles - Hotel California - HD Tracks - 24/96
Head-fi/Chesky Sampler - Open Your Ears - 24/96
Timber and Tonal Balance:
As soon as I plugged the Audiophilleo2 in my audio chain and started to listen to some audio tracks, I knew I was listening to something really special, in a way radically different from the other converters I had been using until then.
In my journey with trying different converters, I had encountered 3 converters that were obvious and non-mistakable upgrades over the ones I had been previously using.
The first one was the stock Hiface. While, in retrospect, it is obviously far from being flawless, it brought nonetheless a sense of realism and “wholeness” to the sound that lesser converters and integrated USB had seemed to not been able to deliver until then. When other converters such as theTeralink-X could have sounded more pleasing to the ears, the Hiface was the most accurate device I had tried until then and especially the only one to make the instruments sound from one piece.
The second one was the battery powered Hiface, also known as JKeny MK1. The battery powered Hiface built upon the strengths of the stock Hiface and provided a much more coherent unit. It was much more impactful, smoother and detailed and it also had a more holographic soundstage.
The third one was the Audiophilleo2. While the gradual improvements of the Hiface and later on the MK1 were expected as I had heard better digital sounding gear elsewhere, the improvements brought by the Audiophilleo2 were hoped for but mostly unexpected.
After using both a Jkeny MK1 and a tweaked A-GD Digital Interface in alternation, I started realizing that although both were very good, neither one was perfect. Meanwhile, given how relatively close sounding they were, I was expecting a hypothetical better converter to be marginally better than the two, but not fundamentally and significantly better.
So I was positively surprised when I plugged in the Audiophilleo2 in my system and heard an unprecedented level of richness of sound and saturation of tone.
Since I got my ALO recabled Beyer T1, I have felt that my system was accurate but (expectedly) not as “warm” as it had been with the Sennheiser HD650s. I attributed that effect (which you can read about in more details in my review of the Beyer T1s) to the nature of the Tesla drivers used in the Beyer T1 and to the fact that I was using a solid state headphone amp with a relatively low output impedance, when Beyer's own headphone am, the A1, has a high output impedance of 120 ohms.
I was already considering getting a tube headphone amplifier but delayed that purchase because I might have to relocate in the next few months and I did not want to burden myself with a heavy tube amplifier. So, indeed, the increase in richness of sound and tone saturation was hoped for through future planned component upgrades but rather unexpected from a source upgrade.
So how does the Audiophilleo2 actually sound in the timber and tonal balance department?
First, I would say that the Audiophilleo2 is very evenly balanced throughout the frequency spectrum. It does not have that mid bass bump that the Teralink converters seem to be plagued with, nor does it have the mid-treble brightness that overly lean converters seem to exhibit in order to fake a higher resolution than they are actually delivering.
The Audiophilleo2 is not only evenly balanced from top to bottom but also capable of reaching very far on both extreme ends of the frequency spectrum.
I would have never described the Beyer T1s as “bassy” headphones until I heard them with the Audiophilleo2 in my reference system. The Beyer T1s do not suddenly become overly warm or unbalanced but the way they cover the frequency spectrum changes a little bit. In my review of the Beyer T1s, I found that while the said headphones had relatively neutral tonal balance, they changed their voicing in dynamic passages. To my ears, it seemed that the Beyer T1s were very dynamic in the mids and highs but lacked impact in the lowest frequencies.
With the Audiophilleo2 in place, the tonal balance of the Beyer T1s remains the same regardless of the dynamic intensity of the passage. Hence, the Beyer T1s appear to be as more impactful headphones. This was a very welcome change but not nearly as obvious or as important as the change in the timber of instruments.
The Audiophilleo2 is really a high resolution device in the sense that it reveals layers of (timbral) information that were previously buried by more jittery converters. It is like if the musicians were using better instruments and the recording engineers were using better microphones and recording chains. Recordings that I had listened to countless times before started revealing new subtleties. Interestingly, even on “poor”quality recordings, the performers seem to be more skilled and their representation less monotonous and more diversified.
With the Audiophilleo2 in place, my system gained both in warmth and in precision. Usually warmth is associated with artificial haze and euphonic qualities. The Audiophilleo2 does it differently as it simultaneously remove a layer of artificial haze and fuzziness and reveals new layers of real natural warmth.
Those who have listened to well-made PMD100+PCM1704uk DACs and compared them to sigma delta DACs (from a lower price range) will probably better understand what I am talking about. It is indeed possible to increase simultaneously the resolution, accuracy of timber and natural warmth parameters without giving up anything in other sectors.
The end result is a highly musical yet accurate representation of the timber of voices and instruments through the Audiophilleo2. Some people might describe the Audiophilleo2 as sharp sounding, and I would agree to some extent because the Audiophilleo2 is not bloated, hazy or overly warm sounding. But contrary to “sharp” sounding components, the Audiophilleo2 does not take away anything from the music: the attack, decay, sustain and release sequence is well preserved with no taking away or emphasis of any part of the sound in the time domain.
Dunedin Consort - Messiah - Linn Records - 24/88: While this high quality recording has always sounded decent on most equipment I have listened to it on, it sounded superb with the Audiophilleo2 as a source on my reference system. Everything sounded coherent and integrated and it seemed like every instrument and performer had his or her own microphone. Even when multiple instruments are playing, every instrument retains its specificity and inner beauty. The choir is very distinct and you can clearly position different performers on the stage.
Natalie Dessay -Italian Opera Arias - Emi Classics - 16/44: Contrary to the Dunedin Consort recordin gcited above, the Natalie Dessay Opera recording is rather an “acid test” in many system. The recording has many tricks on which overly bright components can trip over. One of those difficult passages is track number 12 (Donizetti -Lucia di Lammermoor - Eccola... Il dolce suono), where there is a glass harmonica that can sound very strident on some equipment. Here, not only the glass harmonica sound as good as I ever heard it in my system, but later on the track, the Audiophilleo2 reveals the differences in the timber of voices between the male and the female of the choir. With most converters, the voices in the choir are meshed together but the higher resolving power of the Audiophilleo2 lets the distinction between the different voices appear easily without requiring much effort from the listener.
Alison Krauss andUnion Station - Paper Airplane - 24/96: While this album already sounded good through the A-gd DI, it sounded phenomenal through the Audiophilleo2. The timber of the voice of Alison Krauss is richer are more diversified than ever. listens to this album through the Audiophilleo2, one can easily understand why many high end audiophiles tend to use Alison Krauss albums.
Soundstage and Imaging:
As one gets better and lower jitter converters, one usually gets better soundstaging and imaging qualities. The Audiophilleo2 is no different in this matter as it seems to systematically expand the soundstage of the DAC it is connected to while retaining or improving on the specificity of the imaging.
While the Audiophilleo2 expanded the size of the soundstage of my reference DAC, the audio-gd dac19dsp,its effect was even more impressive on the entry level dac/headphone audio-gd FUN. I had tried many converters with the FUN, and the soundstage size was at best adequate when compared to higher end models. With the Audiophilleo2 in place, the soundstage grew substantially in width, height and depth. It rivals now that of the dac19dsp and I don’t feel deprived anymore when I have to use the FUN.
However, as good as the Audiophilleo2 probably is, I am probably limited with the DACs I have onhand. I just received the newly released Kingrex UD384 async 32/384 USB DAC and it seems to be better than the Audiophilleo2+DAC19DSP in the depth layering at 24/96+ sample rates.
Though, I have to note that it was the case only when using the Kingrex UD384 as a USB DAC and not as a transport (it also has a spdif output). So although the Audiophilleo2+DAC19DSP combination offers fantastic soundstaging, it is most probable that with a different DAC, the results could be even better. [A more complete comparisonbetween the Audiophilleo2 and Kingrex UD384 as transports will be done during the upcoming review of the UD384].
So, the Audiophilleo2 has tremendous soundstaging capabilities, and it is most probable that the limiting factor in many audio chains will probably the DAC itself.
Mahler - Symphony n 5 - Decca - 16/44: In this recording, the Audiophilleo2 gives an impressive sense of depth. The instruments are clearly delineated and differentiated in space. It is really impressive how good a 16/44 recording can be when the transport is of such a high quality as the Audiophilleo2.
Vivaldi - Concerto for 2 violins - Carmignola/Mullova - 16/44: While I mostly use this recording to determine the timber qualities of different components, I was very impressed by the imaging capabilities of the Audiophilleo2 in this album. The two different violins not only sound distinct and wonderful, but I was also able to “follow” the two soloists quite easily, without making much effort. The realism of the representation was such that when I closed my eyes, I was able to “see” the two soloists playing, breathing and moving their arches onto their violins. It was not just two violins hanging in space, but it was two very talented “holograms”of the violinists playing in front of me. Also, the different instruments ofthe accompanying orchestra on the backstage were more defined and distinct than usual.
A question that always kept me wondering is how a digital transport (or cable) can affect the perceived dynamics. It is relatively understandable that stronger and better designed power supplies on the analog portions of the signal can make the signal more dynamic (or at least not hinder its dynamics), but how a digital transport can affect such heavily the perception of the dynamics of an audio chain is a lot more difficult to comprehend?
While I don’t haveany clear cut answer, I suspect that it might have something to do with the way impulse signals are handled. Based solely on my listening, it seems to me that low jitter converters generate (in the analog domain after it has passed theDAC) narrow impulse responses, while high jitter converters generate fatter, less narrow impulse responses. The area (energy) in both cases could be the same (so that there would be no difference when measuring the signal in static mode) yet the fastest more narrow impulse response could track more closely in the time domain what happens in the recording signal.
Regardless of the possible causes and explanations of such a phenomenon, the Audiophilleo2 seems to “turbo-charge”the DAC to which it is connected to.
When listening through my other converters, it seems like the performers are somewhat lazy and tired. When switching to the Audiophilleo2, the performers seem to be better rested, more enthusiastic and alive.
The effect was slightly different between the two main DACs I have tried the Audiophilleo2 with.
When used with the dac19dsp, the Audiophilleo2 seemed to improve on already good DAC offering mainly better micro dynamics and improving the overall refinement of the presentation.
When used with the FUN, it was a totally different story. The FUN came alive and finally became ”fun” to listen to. It was like someone changed the power supply section of the unit and replaced it with a bigger and more powerful one. The scale of change in dynamics was as big as one can usually expect from changing headphone amps when using a challenging headphone. This little experience incidentally helped me understand that the 600 ohms Beyer T1s do not need quantity of amplification nearly as much as they need a high quality source.
Transparency and Definition:
Given what I said in the previous sections above, it is quite obvious that the Audiophilleo2 is a high resolution device, capable of great definition and transparency.
When I first started listening to the Audiophilleo2, I had the impression that I was hearing new details. Obviously, those details were already there since I did not change any major component in my system but those "missing" details were probably buried under the fuzziness and haze that lesser converter colored the sound with. The Audiophilleo2 just made it easier to pick up those details and provided me with a more relaxing less “taxing” listening experience.
Meanwhile, the increase in the saturation of tone and micro-dynamics could definitely be considered as an improvement in resolution/definition. The Audiophilleo2 is capable of tracking much more subtle differences than lesser converters which translates into higher definition and details.
Furthermore, the Audiophilleo2 does not seem to bear any serious coloration. Its transparency is such that it disturbing at first. Even though many audiophiles claim to be chasing neutrality and transparency when they are setting up their systems, many of us (audiophiles) get used to expect a certain level of “consistency” between different albums we listen to.
Terms such as great bass or silky smooth treble are not usually associated with live music, yet we often read audiophiles describe their systems with such words.
With the Audiophilleo2, I encountered something different. When one song can sound veiled, slow or too smooth, the next one can sound bright forward or too dry. I had become used to hearing such things and my natural instinct used to be to look for a way to correct what was “wrong” in my chain by mains of various tweaks or even component changes. Here, I was just hearing what the recordings contained without any “processing”. And while I had some sort of transparency, I had rarely listened to systems with such high level of transparency, which can be disturbing at first.
So, the Audiophilleo2 was not only the highest resolution source I had tried in my system but it also turned the Audiophilleo2+DAC19dsp combination to one of the highest resolution sources I have listened to. And although I like a lot my PCM1704uk based DAC19dsp, I suspect that it might be a limiting factor in this combination.
Operating systems and Media Players:
One of the main reasons I acquired the Audiophilleo2, instead of the JK MK3, when I decided toupgrade my source was due to the fact that the Audiophilleo2 could be run driverless and could also be used under Linux.
While I will be detailing my experiments with different media players and operating systems(XP, Win 7, and various Linux Builds) in an upcoming article, I thought I should mention a relative strength of the Audiophilleo2, which is its relative insensitivity to outside parameters.
It does not mean that you will not hear any differences between media players or between Operating systems but what it means is that the Audiophilleo2 is more “robust” than the other converters I had on hand. One example would be the use of the “Fidelizer”program for windows operating systems. The Fidelizer program does many things in order to give the maximum priority to the audio playback but when I first tried it with the Audiophilleo2, the difference was so small that I thought it was ineffective or that I could be imagining improvements, if they were any. It was until I tried Fidelizer with another async converter, the Kingrex UD384 that I realized that the program was actually working. It was just that the Audiophilleo2 was relatively insensitive to what was happening on the PC side.
In the case of the Audiophilleo2, people can probably use whatever Operating system and media player they feel more familiar with while not losing too much performance over the most "extreme" systems.
Direct Connection vs. Digital SPDIF Cables:
First, it isimportant to remind people that Audiophilleo2 is a very small unit, and as a result of that compactness, the Audiophilleo2 can be plugged directly into the spdif input of the DAC without requiring the use of a digital cable.
Audiophilleo provides different adapters (bnc to bnc, bnc to rca...) to enable that direct link to the dacs.
So I decided to do some comparison between the BNC to BNC adapter and a 1.3m long Oyaide DB-510BNC cable. I was pretty surprised with my findings as there was very little difference between the two methods of connection. The direct connection was perhaps slightly more transparent sounding with a slightly more upfront sound.The Oyaide had a slightly deeper soundstage (induced by some kind of distortion?), but slightly dirtier timber apparent on high quality recordings.
The overall tonal balance is rather similar. And one has to concentrate on individual instruments and voices to expect hearing differences. The differences are so small that I wouldn't be able to tell them apart if I didn't already knew which type of conenction was already in place.
I believe that the lack of differences can be probably be explained by the combination of two factors: the Oyaide is a competently designed spdif cable fully compliant with the 75ohms norm; also, the Audiophilleo2 has a competently built spdif output stage that levels the filed between different cables/connections.
The end result is that unless there is some sort of space issue at the back of the DAC, there is no reason not to use the provided BNC to BNC/RCA connector, as there is no performance gain in throwing $300+ on a high performance digital cable. So when one is looking at the Audiophilleo2 price, one should also consider the fact that he or she will not need to buy a costly high performance digital cable in order to connect the transport to the DAC.
In this case, no cable is actually the best cable.
USB Cables and power supply:
I should probably mention the effect of the usb cable on the Audiophilleo2. When I acquired the Audiophilleo2, I wasn't expecting to hear much difference between usb cable. Indeed, I had noticed very little difference between different usb extenders when I tried them with the battery powered async Jkeny Hiface.
So, when I received the Audiophilleo2, I just used the Wireworld Ultraviolet cable I had been using with my Musiland/Audio-gd DI combo.
After a while, I replaced the Ultraviolet cable with a Belkin USB cable. The sound got warmer and a little bit less defined. The change was subtle but noticeable and repeatable. I quickly went back to the Wireworld Ultraviolet as it was the better cable.
I went back to Audiophilleo website and noticed two things: they admit that usb cables can affect the performance of their converters (as some usb cables can attenuate the usb power noise), and they are offering the same wireworld ultraviolet cable I have been using for more than 2 years with their Audiophilleo1 (the full feature model of the Audiophilleo2).
However, given that we are not dealing here with usb framing jitter, it might not be beneficial to invest in a higher end usb cable. It is most probable that something like the low noise USB power supply offered by Aqvox might provide a better lift in performance than a similarly (high) priced USB cable.
I will report back whenever I get a chance to try an external power solution.
Conclusion – The last USB to Spdif converter you willever need?
The Audiophilleo2 is a fantastic USB converter and audio transport. It has lifted considerably the performance of my system in many areas and I was sometimes surprised by the scale of the improvement.
While I didn’t detail the impact of the Audiophilleo2 DAC by DAC, I found that its effect was rather consistent from one system to another. When putting Audiophilleo2 in any audio chain, there is an overall improvement regardless of what components are being used downstream. Even my entry level Little Dot MKIII sounded better than I ever remembered. That is to say that whether you are using low end or high end equipment, the effect of the Audiophilleo2 on the system seems to be cost effective and well worth it.
Does it mean that the Audiophilleo2 is perfect sounding? The answer is obviously no. As good as the Audiophilleo2 sounds, one has to keep in mind that it is built with some economic and physical constraints: limited physical size, USB power supply, “regular” clocks (very good, but perhaps not the absolute best) … So if money were no object, there are obvious areas of improvements that would probably make the Audiophilleo2 sound even better.
In fact, people have already reported that using external power supplies (battery or linear power supplies) instead of the 5V coming through the USB port provided noticeable improvements. Also, Audiophilleo is rumored to be working on a battery powered version of the Audiophilleo 1 and 2.
However, even though I suspect that something similar to an Empirical Audio Offramp 4 with the DualTurbo Clocks and the optional battery power supply might outperform the Audiophilleo2, it is possible that the Audiophilleo2 is the last USB to spdif many audiophiles will want to buy.
The reason is simply that spdif is an outdated means of transmitting digital audio streams. A well designed direct USB input is theoretically capable of much better performancethan USB + SPDIF. Indeed, converters such as the Audiophilleo2 have reached single digit jitter numbers (in ps), while most spdif receivers have already between 50ps and 200ps of intrinsic jitter. So we are reaching a point where SPDIF will start becoming a clear bottleneck in the digital section and audiophiles will be encouraged to move to either I2S (with very short cables) or to direct USB. The latter option seems the most convenient and practical in my personal opinion as it reduces the number of components and cables being used in the audio chain.
To sum up, I will just copy over what I already wrote in my preliminary impressions, as my opinion didnot change about the Audiophilleo since then.
The guys over at Audiophilleo seem to have accomplished what we do not seem to witness very often in the audiophile world: they made a product that measures extremely well, that sounds awfully good, and that is very convenient to use.
Just as I was finishing this review, a head-fier asked me if I had compared the Audiophilleo2 with the JKeny MK3. The answer is no as the only battery powered Hiface I have had in my system is the MK1. Although I have not listened to the MK3, here is my personal point of view on the subject: I have read that the Audiophilleo2 and the MK3 are somehow performing at a rather similar level. Given that the performance of the MK3 is already “maxed out” since it uses battery power and that there is still roomfor improvement for the Audiophilleo2 through trying different power supplies,I would say that for a “tweaker”, it might be interesting to get the Audiophilleo2. Also, the main reason that encouraged me to get the Audiophilleo2 instead of the MK3 is the poor driver support by M2Tech. Indeed, since the launch of the Hiface, M2Tech has promised Linux drivers but, as far as I know, never delivered anything; also, there have been a few issues with audio/video synchronization that do not seem to make a high priority rank in the M2tech roadmap. Those things might or might not be an issue depending on the needs of the user; also I should note that JKeny is not responsible for the drivers since he is only using the boards provided by M2Tech. Overall, until we get more more independant comparisons and reviews of the Audiophilleo against JK MK3, people can only speculate and both units seem to make a lot of happy people for their asking price.